1. Field of the Invention
The present invention relates to an ultrasonic diagnostic apparatus, an ultrasonic diagnostic method, and a control processing program for the ultrasonic diagnostic apparatus, in particular, an ultrasonic diagnostic apparatus, an ultrasonic diagnostic method, and a control processing program for the ultrasonic diagnostic apparatus in which tracking of a sample marker of spectrum Doppler can be performed in accordance with movement of a blood vessel.
2. Description of the Related Art
In recent years, an ultrasonic diagnostic apparatus has been proposed which is capable of displaying a tomographic image (a B mode tomographic image) and blood flow information in real time by using an ultrasonic Doppler method, an ultrasonic pulse reflection method, and other methods in combination.
The ultrasonic Doppler method used in combination with the ultrasonic pulse reflection method can be roughly divided into two methods: a spectrum Doppler method of displaying a temporal change in a Doppler frequency corresponding to the speed of the blood current and a color Doppler method of color displaying information such as the blood current speed and variance.
When blood flow information inside the blood vessel or the like is observed by using the spectrum Doppler method, in order to observe blood flow information of a desired blood vessel, a sample marker for detecting the blood flow information of the desired position needs to perform a tracking in accordance with a movement of the desired blood vessel. For that reason, up to now, as a method of tracking the sample marker, a doctor or a technician (hereinafter referred to as “operator”) manually performs an adjustment of the position of the sample marker so that the position of the sample marker is matched to the moved position of the blood vessel desired to be observed.
However, in a case where, for example, a coronary artery (blood vessel) present in the vicinity of the heart is observed with use of the manual tracking method by the operator, as the coronary artery relatively largely moves along with a beat of the heart, it is difficult for the operator to adjust the position of the sample marker in accordance with the movement of the coronary artery (blood vessel) for allowing the sample marker to track the coronary artery (blood vessel).
Also, the position of the blood vessel is moved due to a breathing, a motion, or the like of a patient (hereinafter referred to as “subject body”). Therefore, the operator needs to frequently perform an adjustment of the position of the sample marker and there is a problem of the troublesome adjustment operation.
In view of the above, an ultrasonic diagnostic apparatus has been proposed in which the automatic tracking of the sample marker can be performed in accordance with the observation position, operational burdens on the operation can be alleviated, and it is possible to shorten the diagnosis time.
According to an ultrasonic diagnostic apparatus proposed in Japanese Unexamined Patent Application Publication No. 6-217975, the automatic tracking of the sample marker is performed with use of blood flow information of a color Doppler in a two dimensional fault, and even when the blood vessel is moved, blood flow information of the blood vessel desired to be observed can be obtained.
Also, such an ultrasonic diagnostic apparatus has been proposed that a blood flow direction is automatically detected in addition to the automatic tracking of the sample marker and a Doppler angle is calculated on the basis of the detected blood flow direction to suppress an error to minimum due to mismatching between a direction of an ultrasonic wave beam and the blood flow direction.
According to an ultrasonic diagnostic apparatus proposed in PCT Japanese Translation Patent Publication No. 2003-523250, a measurement accuracy for a blood flow speed can be increased.
However, in the ultrasonic diagnostic apparatuses proposed in Japanese Unexamined Patent Application Publication No. 6-217975 and PCT Japanese Translation Patent Publication No. 2003-523250, the automatic tracking in the two dimensional fault is performed while using a plurality of ultrasonic wave transducer elements arranged in an array in a one dimensional manner. Thus, the tracking is possible with respect to the blood vessel movement in the two dimensional cross-section. However, the blood vessel inside the subject body moves in a three dimensional manner including a depth direction with respect to the cross-section. When the blood vessel desired to be observed moves in the depth direction with respect to the cross-section, it is difficult to perform the tracking of the sample marker in accordance with the movement of the blood vessel.
In particular, when a diagnosis is performed after administration of a medicine to the subject body, the blood vessel inside the subject body largely moves in a three dimensional manner including the depth direction with respect to the fault plane as compared with a normal condition, and it is more difficult to perform the tracking of the sample marker in accordance with the movement of the blood vessel desired to be observed.